• Journal of Microbiology and Biotechnology
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• 제25권1호
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• pp.26-32
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• 2015

Four types of straw, namely, soybean, wheat, corn, and rice, were investigated for use in lactic acid production. These straws were mainly composed of cellulose, hemicellulose, and lignin. After pretreatment with ammonia, the cellulose content increased, whereas the hemicellulose and lignin contents decreased. Analytical results also showed that the liquid enzymatic hydrolysates were primarily composed of glucose, xylose, and cellobiose. Preliminary experiments showed that a higher lactic acid concentration could be obtained from the wheat and soybean straw. However, soybean straw was chosen as the substrate for lactic acid production owing to its high protein content. The maximum lactic acid yield (0.8 g/g) and lactic acid productivity (0.61 g/(l/h)) were obtained with an initial reducing sugar concentration of 35 g/l at 30℃ when using Lactobacillus casei (10% inoculum) for a 42 h fermentation period. Thus, the experimental results demonstrated the feasibility of using a soybean straw enzymatic hydrolysate as a substrate for lactic acid production.

• Restorative Dentistry and Endodontics
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• 제22권2호
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• pp.637-647
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• 1997

The purpose of this study was to evaluate the effect of concentration and pH of lactic acid on the formation of artificial root caries lesions formation in bovine teeth. The characterictics of artificially produced early root lesions were observed with polarized light microscope and the depth of lesions were mearsured with measuring microscope The results were as follows: 1. In the group of low pH and high concentration of lactic acid, the progress of lesion formation was faster than that of high pH and low concentration lactic acid group. 2. In the same group, initial lesion progress faster, but progression rate was reduced as time goes by. 3. In the development of initial root caries, cementum was act as a barrier to protect dentin from lesion progression.

• 치위생과학회지
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• 제7권1호
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• pp.21-24
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• 2007

본 실험에서는 S. mutans KCTC 3065을 이용하여 lactic acid를 첨가하였을 때 일어나는 스트레스 반응을 살펴보고자 하였으며 다음과 같은 결론을 얻었다. 1. 배지에 lactic acid를 농도별로 첨가하여 농도에 따른 생육저해현상을 조사한 결과, 배 지에 첨가 된 lactic acid의 함량에 비례하여 S. mutans의 성장이 완만해지며, 지수증식기일 때 lactic acid를 첨가 하였을 경우 유도기일 때 lactic acid를 첨가한 경우보다 균의 성장이 활발한 것을 알 수 있었다. 2. 대수증식기의 균주를 취하여 0, 60, 70, 80 mM 농도의 lactic acid를 처리한 후 colony의 생성으로 균주의 생존유무를 관찰한 결과, 70 mM의 농도로 lactic acid를 처 리하고 90분후부터는 colony의 밀도가 급격히 낮아지며생존에 영향을 받는 것을 관찰할 수 있었으며, lactic acid의 농도가 80 mM이상 에서는 생존이 거의 불가능한 것으로 나타났다. 3. Acid stress 동안에 지방산 조성의 변화를 관찰한 결과, $C_{18:1}$은 30.92%에서 33.89%로 증가하였으며 $C_{14:0}$은 5.02%에서 2.62%로 $C_{16:0}$은 39.16%에서 33.69%로 감소하였다. 4. Acid stress 동안에 단백질 패턴의 변화를 관찰한 결과, 약 70 kDa, 60 kDa, 45 kDa, 40 kDa 그리고 23 kDa의 단 백질 발현이 증가되는 것을 볼 수 있었다.

• 생명과학회지
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• 제12권6호
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• pp.812-820
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• 2002

이 연구는 주변의 김치들을 수거하여 젖산에 내성을 가진 Leuconostoc mesenteroides을 선택배지를 이용하여 분리하고, 지방산 조성을 분석하여 동정한 결과, Leuconostoc mesenteroides LM3균주로 동정했다. 이어서 그의 성장패턴을 관찰하고, 유도기와 지수성장기에서 젖산을 첨가한 결과 성장저해가 일어났음을 확인했으며, 젖산의 최종농도가 0.4%이상인 배지에서는 성장속도가 느려짐을 알았다. 그리고 정지기시작단계에서 고농도의 젖산을 단시간 처리하였을 때, 대조균주가 생존하지 못하는 4%농도에서도 Leuconostoc mesenteroides LM3군주가 생존하는 것을 확인하여 산에 대한 내성이 뛰어남을 알 수 있었다. 이에 trehalose 농도의 변화, 그리고 trehalase와 ATPase 활성을 측정하였고, 이를 통해 젖산에 의한 세포내의 변화를 관찰하였다. 그 결과, 각 성장시기별로 0.6% 젖산을 첨가했을 때 Leuconostoc mesenteroides LM3균주가 trehalose 축적률이 높아졌으나 trehalase활성엔 큰 변화가 없었다. ATPase 활성은 감소하는 경향을 보였으나 시기별 활성은 일정하였고, 세포내 pH를 측정한 결과 Leuconostoc mesenteroides LM3균주는 pH 6으로 일정하게 유지되었다.

• 생약학회지
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• 제18권1호
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• pp.34-40
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• 1987

Onion extracts were tested for effects on the growth and lactic acid production of Lactobacillus bulgaricus in the medium containing mercury. The media containing mercury were added with onion extracts and inoculated with the bacterium and then incubated at $39^{\circ}$ for four days. All of the onion extracts examined increased the growth and lactic acid production of the bacterium in the medium containing mercury. At the addition of the edible portion extract of onion to the medium containing 5 ppm, 10 ppm and 20 ppm mercury, the higher the concentration of the onion extract was added, the greater the increasing effect on the growth and lactic acid production. The brown peel extract of onion increased the growth and lactic acid production of the bacterium in the medium containing mercury at all concentrations. The higher the concentration of the extract added, the more effective the increasing effect. The onion solutions of edible portion and brown peel extracted at $90^{\circ}\;to\;100^{\circ}$ showed more desirable effects than those extracted at the room temperature. Among four kinds of the onion extracts, the brown peel solution extracted at $90^{\circ}\;to\;100^{\circ}$ was the most effective in increase of the growth and lactic acid production in the medium containing mercury.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권1호
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• pp.23-28
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• 2005

Lactic acid is a green chemical that can be used as a raw material for biodegradable polymer. To produce lactic acid through microbial fermentation, we previously screened a novel lactic acid bacterium. In this work, we optimized lactic acid fermentation using a newly isolated and homofermentative lactic acid bacterium. The optimum medium components were found to be glucose, yeast extract, $(NH_4)_{2}HPO_4,\;and\;MnSO_4$. The optimum pH and temperature for a batch culture of Lactobacillus sp. RKY2 was found to be 6.0 and $36^{\circ}C$, respectively. Under the optimized culture conditions, the maximum lactic acid concentration (153.9 g/L) was obtained from 200 g/L of glucose and 15 g/L of yeast extract, and maximum lactic acid productivity ($6.21\;gL^{-1}h^{-1}$) was obtained from 100 g/L of glucose and 20 g/L of yeast extract. In all cases, the lactic acid yields were found to be above 0.91 g/g. This article provides the optimized conditions for a batch culture of Lactobacillus sp. RKY2, which resulted in highest productivity of lactic acid.

• 한국식생활문화학회지
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• 제29권3호
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• pp.286-297
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• 2014

This study was conducted to evaluate the growth of lactic acid bacteria and quality characteristics of Baechu kimchi prepared with four types of salt (Solar salt, Flower salt, Hanju salt, and Roasted salt) at two different concentrations (10, 15%) during storage. The quality characteristics of kimchi were examined by investigating acid production, growth of lactic acid bacteria, sensory properties, salinity, texture, and color characteristics. Baechu kimchi was fermented for 18 days at $10^{\circ}C$. The pH and total acidity did not change during storage according to type and concentration of salt. Growth of lactic acid bacteria was not affected by type of salt, whereas it was inhibited at 15% salt concentration after 9 days of fermentation. In the quantitative descriptive analysis of sensory properties, kimchi prepared with 10% salt showed significantly higher scores in term of overall acceptability (p<0.05). Meanwhile, there was no significant difference by type of salt. For texture characteristics, hardness of kimchi prepared with 10% salt was significantly higher than that with 20% salt. For color characteristics, L value (brightness) and b values (yellowness) of kimchi prepared with 10% salt increased during fermentation, whereas a value (redness) did not change by type and concentration of salt. The results of this study show that there were no considerable differences in quality characteristics of Baechu kimchi prepared with various types and concentrations of salt. However, Solar salt resulted in more favorable sensory properties and salinity of kimchi than any other types. Further, kimchi prepared with 10% salt showed significantly higher scores in terms of overall acceptability, growth of lactic acid bacteria, salinity, texture, and color characteristics.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.218-221
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• 2003

Lactic acid fermentation from sucrose as a carbon source was experimented. E. faecalis RKY1 metabolized sucrose efficiently into lactic acid through homolactic fermentation pathway. The optimal sucrose concentration for lactic acid production was found to be 150 g/l with the yield and productivity of 0.97 g/g and $3.7\;g/l\;{\cdot}\;h$, respectively. Lactic acid produced from sucrose was almost L(+)-lactic acid up to 98% based on total lactic acid produced. Therefore, sucrose was thought to be potential carbon source for L(+)-lactic acid production using E. faecalis RKY1.

• KSBB Journal
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• 제14권2호
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• pp.212-219
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• 1999

섬유성바이오매스로부터 lactic acid를 생산하기 위한 동시당화 및 추출발효공정의 성능과 조업특성을 조사하였다. 섬유소 가수분해효소 Cytolase CL과 lactic acid 발효군주 L. delbruecku를 사용한 동시당화발효(SSF)에서 생성물인 lactic acid의 저해작용이 심각하였다. SSF 도중 lactic acid의 제거를 위하여 선정한 IRA-400 수지의 lactic acid 흡착성능은 200mg/g dry resin 이었다 Lactic acid 제거의 효과는 초기 기질(cellulose)의 농도에 따라 Lactic acid 제거의 효과는 초기 기질(cellulose)의 농도에 따라 다르게 나타난다. 기질의 농도가 50g/L인 경우 단순 SSF의 반응시간 72시간에서 lactic acid의 농도가 304g/L이었고, 이온교환수지를 첨가한 SSF에서는 32.0g/L이었다. 반면에, 모사실험 결과, 초기 기질사용량이 100g/L 인 경우에는 수지첨가에 의한 lactic acid 제거시 lactic acid 생산수율이 약 60%에서 90%이상까지 증가된다. SSF의 각 반응식에서 pH의 의존성을 조사하여 실험식으로 표현하였다. pH에 따라 lactic aic의 생산량이 크게 변화하였으며, pH 4.5-5.0에서 최대의 생산량을 나타내었다.

• Asian-Australasian Journal of Animal Sciences
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• 제19권3호
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• pp.386-389
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• 2006

Silage is a major component of cattle rations, so the improvement of silage quality by the inoculation of lactic acid bacteria is of great interest. In this study, commercially distributed Lactobacillus plantram and Lactobacillus rhamnousas NGRI 0110 were used for ensilaging of guinea grass. The four treatments used were a control silage, a silage with cellulase addition, a silage with cellulose+L. plantram addition, and a silage with cellulose + NGRI 0110 addition. Silage quality, voluntary intake, nutrient digestibility, and the characteristics of ruminal fluid of wethers were investigated. Silage to which lactic acid bacteria were added showed low pH and acetic acid concentration and the highest lactic acid content. Dry matter and organic matter digestibility were significantly (p<0.05) increased by cellulase addition and significantly (p<0.05) higher values were observed in L. plantram- and NGRI 0110-added silage. Voluntary intake of NGRI 0110-added silage was the highest and that of control silage was the lowest. We concluded that the observed ability of NGRI 0110 to tolerate low pH and to continue lactic acid fermentation in high lactic acid concentration had also occurred in actual ensilaging. The results indicate that the addition of lactic acid bacteria might improve silage quality and increase digestibility and voluntary intake. The potential for improvement by NGRI 0110 was higher than that to be gained by the use of commercially available lactic acid bacteria.